The invention relates to digital imaging devices, such as active pixel sensor and CCD arrays.
Digital imaging devices such as active pixel sensor (APS) and charge-coupled device (CCD) cameras include many image sensors arranged into arrays of columns and rows. Each image sensor collects electrical charge when exposed to light. Control signals provided to the image sensors periodically enable the sensors to transfer the collected charge, or voltage-mode signals derived from the charge, to an imaging circuit.
The inventor has recognized a desire to reduce a necessary number of control lines for a given application that drive the image sensors in a digital imaging array. One technique for reducing the number of control lines is to provide multiple control signals on lines that are shared by adjacent rows of sensors in the array. Many advantages result, including greater space resolution in the sensor array, reduced interlevel (e.g., metal to polysilicon) contacts in the APS circuit, and higher quantum efficiency for the sensors.
In one aspect, the invention features a digital imaging device that includes a plurality of image sensors arranged into an array of lines including rows and columns. At least one output line connects to the image sensors. A control line connects electrically to at least two different image sensors in two different lines. The control line delivers a select signal to at least one image sensor in one of the lines and delivers a reset signal to at least one image sensor the other line. The select signal causes the image sensor in the first line to place an output signal on the output line, and the reset signal clears information from the image sensor in the second line.
In another aspect, the invention features a digital imaging system that includes a plurality of image sensors arranged into an array of lines forming rows and columns. Each of the image sensors includes a photosensor that collects electric charge when exposed to light, a select circuit that generates an output signal indicating the amount of electric charge collected by the photosensor, and a reset circuit that removes collected charge from the photosensor. The system also includes a line decoder circuit. This circuit includes a plurality of control lines and a control circuit that delivers select signals and reset signals over the control lines. Each control line connects to image sensors in two lines of the array. Each control line delivers a select signal to the select circuits in one of the two lines and delivers a reset signal to the reset circuits in the other of the two lines.
In another aspect, the invention features a method for use in capturing an image with a plurality of image sensors arranged into an array of lines forming rows and columns. A select signal is delivered to at least one image sensor in a first one of the lines, and a reset signal is delivered to at least one image sensor in a second one of the lines. The select signal and the reset signal are delivered over a single control line. In response to the select signal, an output signal is delivered from the image sensor in the first line, and information is cleared from the image sensor in the second line.
Other embodiments and advantages are apparent from the following description and from the claims.